Roll mill



FIG. 1 is a front and upper perspective view of a roll mill embodied in accordance with my design;

FIG. 2 is a front view thereof (a rear view is represented identically with the front view);

FIG. 3 is a left side view thereof (a right side view is represented identically with the left side view);

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a roll mill, as shown and described. 